1. Technical Field
The present invention relates to a semiconductor integrated circuit, and more particularly, to an internal voltage generator that is supplied with an external voltage and generates an internal voltage which is used in a semiconductor integrated circuit.
2. Related Art
In general, an internal voltage generator is supplied with an external voltage VDD, and generates an internal voltage VINT whose potential level may be various different levels. Specifically, the internal voltage generator is supplied with a high external voltage and generates a low internal voltage for an internal circuit. A semiconductor integrated circuit operates by using the low internal voltage. Therefore, it is possible to reduce power consumption of the semiconductor integrated circuit and improve a function thereof.
The internal voltage generator that generates the internal voltage may include various drivers. For example, the drivers may include a standby driver and an active driver. The standby driver may be a small-amount driver that is constantly activated to supply an internal voltage, but has low power consumption. Generally, a discharge transistor, through which a current of a few microamperes flows, is used in the standby driver. The reason why the discharge transistor is used is to stably maintain the internal voltage so as to stably perform a circuit operation.
The active driver may be a large-amount driver that sufficiently supplies an internal voltage during an active mode when the semiconductor integrated circuit is operated. In particular, because of the power consumption, the active driver only operates when the semiconductor integrated circuit becomes active, which reduces the amount of current that flows through the active driver.
When the semiconductor integrated circuit becomes active, the active driver is activated. Further, as circuits using the internal voltage VINT operate, an external voltage needs to be supplied. However, because of an operational characteristic of the active driver which supplies a large amount of current, the active driver may supply an excess voltage with respect to the required internal voltage. In this case, the discharge circuit that is included in the standby driver discharges the excess voltage so as to maintain the internal voltage at a predetermined potential level. However, it may take too long of a time to discharge the excess voltage by using only the discharge circuit. Further, area efficiency of the semiconductor integrated circuit may decline due to the additional discharge circuit.